Blood levels of oxytocin and vasopressin during suckling in the rabbit and the problem of their independent release

Bisset, G. W.; Clark, Barbara J.; Haldar, Jaya

doi:10.1113/jphysiol.1970.sp009039

Cited by 50 publications

(27 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…37,47). Because under natural conditions rabbits are often both pregnant and lactating (8,38,51), the sudden surge in blood-born OT accompanying nursing (6,12,21,26) could induce abortion or premature birth were it not timed to occur during the period of minimum uterine sensitivity to OT, that is, during the night (43). The present findings thus show a close correspondence between uterine sensitivity to OT and the previously reported diurnal partitioning of nursing and parturition in this species (Ref.…”

Section: Discussionsupporting

confidence: 69%

“…41, 47) just once every 24 h for ϳ3 min (13,38,40,51,68), at which time the pups drink up to 25% of their body weight (38,40,51). This rapid milk transfer depends on the large and sudden release of OT into the mother's bloodstream in response to sucking by the young (6,12,21,26). Rabbits also have a marked postpartum estrus and, under natural conditions, are often both pregnant and lactating (8,38,51).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Effect of photoperiod on the mechanical response of the pregnant rabbit uterus to oxytocin

Ninomiya-Alarcon

Hudson²,

Reyes-Guerrero³

et al. 2004

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

We present findings suggesting that photoperiod is important in determining the sensitivity of the late-pregnant rabbit uterus to oxytocin (OT). Longitudinal myometrial strips were taken from term-pregnant and estrous rabbits and mounted in an organ bath for isometric myographic recording at different times during a 16:8-h light-dark cycle (lights on 0600 -2200; n ϭ 5/group), and the strength of contractions was registered in response to the application of OT or KCl. Strength of contractions was dose dependent and was up to 200 times greater at doses three to four orders of magnitude lower in tissue taken from pregnant animals during the light phase (0700 and 1300) than during the dark phase (2400 and 0400). Strips from nonpregnant estrous females also showed greater sensitivity and contractile force when taken in the light (0700) than in the dark (0400), although the differences were not significant. Consistent with the influence of photoperiod on uterine sensitivity to OT, strips taken from two groups of pregnant females (n ϭ 5/group) maintained on a light-dark cycle advanced 12 h showed significantly greater sensitivity and force in response to OT during the new subjective light than during the new subjective dark phase. The photoperiod-dependent contractile response to OT was specific and not simply the result of a change in general mechanical properties of the muscle, because administration of KCl resulted in dose-dependent contractions of similar magnitude in both the light and dark phase. These results are consistent with the fact that rabbits, like other nocturnal mammals, typically give birth during the day. parturition; electromyographic uterine recording; circadian rhythmicity MUCH EFFORT HAS BEEN DIRECTED to understanding the processes triggering parturition, and although this is still not completely understood, some common features are emerging. One is that parturition has a strong diurnal component such that mammals usually give birth during their species-typical rest period (reviewed in Refs. 14,35,36,54): nocturnal mammals such as the rat during the day (28, 39, 52, 61) and diurnal mammals such as sheep (Ref. 30; own observations), monkeys (15,16,56), and humans (9,10,29,49,55,64) during the night. Moreover, in humans, births occurring at night are typically of shorter duration, require fewer interventions, and have an obstetrically better outcome than births occurring during the day (Refs. 3,9,55,60; reviewed in Ref. 36).A second common feature is the importance of the hormone oxytocin (OT), released at the time of parturition from the posterior pituitary into the bloodstream, in helping to initiate and sustain the uterine contractions necessary for expulsion of the fetus(es) (1, 11, 12, 17, 19, 23-25, 31, 33, 50, 67). In those species in which it has been studied, principally macaque monkeys and humans, there is a diurnal rhythm in circulating levels of OT, with the highest levels at night (18,20,33,34,36,65). This rhythm becomes more pronounced as gestation progresses and is most marked at the...

show abstract

Section: Discussionsupporting

confidence: 69%

mentioning

confidence: 99%

Effect of photoperiod on the mechanical response of the pregnant rabbit uterus to oxytocin

Ninomiya-Alarcon

Hudson²,

Reyes-Guerrero³

et al. 2004

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

show abstract

“…Evidence from other species confirms the view that suckling is a highly selective stimulus for the release of oxytocin. In the rabbit, for example, Bisset et al (1970) found that oxytocin appeared in the circulation during suckling without vasopressin. During the milking of cows, Legros, Reynaert & Peeters (1974) found that neurophysin I (i.e.…”

Section: Background Activity Of So Units During Sucklingmentioning

confidence: 99%

“…Four of the phasically active units were correlated with the oxytocin release for milk ejection. Three of these units displayed a burst of activity superimposed on the terminal portion ofan active phase, some 10 2-14*7 see INTRODUCTION The neurosecretory cells of the paraventricular (PV) and supraoptic (SO) nuclei of the hypothalamus have axons projecting to the neurohypophysis and form the efferent pathway for the neuroendocrine reflexes involved in the release of oxytocin and vasopressin following stimuli such as suckling (Folley & Knaggs, 1966;Bisset, Clark & Haldar, 1970), expansion of the birth canal (Roberts & Share, 1968;Haldar, 1970), dehydration (Jones & Pickering, 1969) and haemorrhage (Ginsburg & Brown., 1956;Bisset, Clark & Errington, 1971). PV and SO units have been identified in many studies by antidromic activation from the neurohypophysis (Yagi, Azuma & Matsuda, 1966;Cross, Novin & Sundsten, 1969) and the characteristics of their antidromic activation have been extensively investigated by extracellular (Dreifuss & Kelly, 1972a, b;Negoro & Holland, 1972;Barker, Crayton & Nicoll, 1971) and intracellular recording (Koizumi & Yamashita, 1972).…”

mentioning

confidence: 99%

Electrophysiological evidence for the activation of supraoptic neurones during the release of oxytocin

Lincoln¹,

Wakerley²

1974

The Journal of Physiology

258

124

View full text Add to dashboard Cite

SUMMARY1. Antidromically identified supraoptic (SO) units were recorded in lactating rats anaesthetized with urethane (1.1 g/kg), and their activity was studied during milk ejection evoked by the suckling of the young. Fifty-eight SO units were recorded through 174 milk ejections. Each milk ejection was the result of a neurohypophysial release of an oxytocin pulse of 0.5-1-5 m-u.2. Fifty-five of the SO units displayed background activity and three were silent. The firing rates ranged from 0 to 15-4 spikes/sec, the distribution was exponential with 26 % of the units firing at < 1 spike/sec. Sixteen (28 %) of the SO units displayed a phasic pattern of activity characterized by periods of activity (6-132 sec) and silence (4-71 sec).3. Twenty-five of the non-phasic units displayed a large and stereotyped acceleration in spike activity some 10-5-17-4 see before the rise in intramammary pressure at milk ejection. Units accelerated to rates between 9-66 spikes/sec, an increase of about thirtyfold (median) on background activity. The response was brief (0.9-4.7 see) and was followed by a period of after-inhibition.4. It was concluded from studies of double recordings and observations of multi-unit activity that all the responsive units were synchronously activated. The mean latency of 13-3 sec between the onset of the neurosecretory response and milk ejection was similar to that observed following the experimental release of endogenous oxytocin by electrical stimulation of the neurohypophysis (50 pulses/sec for 2-4 sec).5. Four of the phasically active units were correlated with the oxytocin release for milk ejection. Three of these units displayed a burst of activity superimposed on the terminal portion ofan active phase, some 10 2-14*7 see

show abstract

“…OT, the twin neuropeptide of AVP, governs milk ejection after its release from the axon terminals of hypothalamic magnocellular neurons into the blood stream (Bisset et al 1970). During lactation, OT gene expression and OT immunoreactivity are increased in the magnocellular neurons of both the PVN and supraoptic nucleus (Wigger & Neumann 2002).…”

Section: Introductionmentioning

confidence: 99%

Blunted HPA axis response in lactating, vasopressin-deficient Brattleboro rats

Fodor¹,

Pintér²,

Domokos³

et al. 2013

Journal of Endocrinology

View full text Add to dashboard Cite

Adaptation to stress is a basic phenomenon in mammalian life that is mandatorily associated with the activity of the hypothalamic-pituitary-adrenal (HPA) axis. An increased resting activity of the HPA axis can be measured during pregnancy and lactation, suggesting that these reproductive states lead to chronic load in females. In this study, we examined the consequences of the congenital lack of vasopressin on the activity of the HPA axis during lactation using vasopressindeficient Brattleboro rats. Virgin and lactating, homozygous vasopressin-deficient rats were compared with control, heterozygous rats. In control dams compared with virgins, physiological changes similar to those observed in a chronic stress state (thymus involution, adrenal gland hyperplasia, elevation of proopiomelanocortin mRNA levels in the adenohypophysis, and resting plasma corticosterone levels) were observed. In vasopressin-deficient dams, adrenal gland hyperplasia and resting corticosterone level elevations were not observed. Corticotropinreleasing hormone (Crh) mRNA levels in the hypothalamic paraventricular nucleus were elevated in only the control dams, while oxytocin (OT) mRNA levels were higher in vasopressin-deficient virgins and lactation induced a further increase in both the genotypes. Suckling-induced ACTH and corticosterone level elevations were blunted in vasopressin-deficient dams. Anaphylactoid reaction (i.v. egg white) and insulin-induced hypoglycemia stimulated the HPA axis, which were blunted in lactating rats compared with the virgins and in vasopressin-deficient rats compared with the controls without interaction of the two factors. Vasopressin seems to contribute to the physiological changes observed during lactation mimicking a chronic stress state, but its role in acute HPA axis regulation during lactation seems to be similar to that observed in virgins. If vasopressin is congenitally absent, OT, but not the CRH, compensates for the missing vasopressin; however, the functional restitution remains incomplete.

show abstract

Blood levels of oxytocin and vasopressin during suckling in the rabbit and the problem of their independent release

Cited by 50 publications

References 26 publications

Effect of photoperiod on the mechanical response of the pregnant rabbit uterus to oxytocin

Effect of photoperiod on the mechanical response of the pregnant rabbit uterus to oxytocin

Electrophysiological evidence for the activation of supraoptic neurones during the release of oxytocin

Blunted HPA axis response in lactating, vasopressin-deficient Brattleboro rats

Contact Info

Product

Resources

About